Techie's Corner - Fire and more fire.

Last
month we discussed what fire could do, some of the moods it could evoke
and some situations and reasons for using it. For a review, please read
last month’s article available in the back issues of TRE. As with past
articles, the illustrations are not currently supported by our archive
storage. So, if you read the article and would like to see the
illustrations, please feel free to contact me and I will send them to
you.

Last month we looked at a battery
operated fire effect. This month I will describe a line voltage (USA
120VAC) device. This device can be made to imitate the flickering of a
fire, a TV set or any other low level, random flickering light source.
The device involves a 15 to 40 watt, 120 volt lamp, and a fluorescent
starter and miscellaneous wiring for each lamp you use in the
effect. Note: There are many types and brands of starters and some
starters will need a ballast to provide sufficient power to operate the
lamp. If your circuit does not work without a ballast, it will be
cheaper to buy another type of starter than to buy a ballast. The
starters cost between $ .50 and $3.00, ballasts run $15 to $30 each.

The starter is the main ingredient in the mix. Starters are the small silver cylinders about

1
½” long and about ¾” around that fits into one end of older type
fluorescent fixtures. They are available at most home improvement
stores, hardware stores, Home Quarters, Home Depot et. al. A starter is
basically an electrical capacitor that gives a short boost of voltage
to start the old style (slow start) type of fluorescent lamps and then
turns off. In a fluorescent fixture the starter is then out of the
circuit until the switch is turned off and then on again. In our
effect, the starter is wired in series with the lamp and is “in the
circuit” all the time. When the switch is turned on, the starter is
“off” but it starts storing up voltage. At a certain point the voltage
builds up and “overflows” causing the lamp to light up. The starter is
now “empty” of electricity and “shuts off” causing the lamp to be dark.
It is kind of like a bucket under a faucet that is hinged to tip over
when the bucket is full and to tip back up when it is empty. In the
fluorescent fixture the starter only operates once each time the
fixture is turned on, therefore it is not important just how consistent
or accurate the starter is. The impreciseness helps in our circuit
because no two lamps will blink at the same rate.

For
most fire effects, at least three or four lamps should flicker and one
should be on for a steady background effect. If physical space in your
fire unit permits, as many as nine or ten lamps may be used. As you
increase the number of lamps you can lower the wattage. However a mix
of different wattages makes a more realistic effect.

To
wire your effect you will need a starter for each lamp, a socket for
each lamp, a male Edison plug, wire, wire nuts, a plywood (or similar)
base. You may wire a switch into the circuit or design the wiring to
plug into a switch box that you already have on hand. The most critical
part of the wiring is the starter. There are two small prongs on one
end, most look like the head of a nail that is sticking out about
¼”.The starter should be fastened down in some way, hot glue, plumber’s
strap, heavy rubber band, Velcro strap etc.The wiring must not contact
the outer case of the starter in any way. The easiest way to connect to
the starter is to use small, insulated alligator clips available at
Radio Shack. This makes changing the starter very easy if necessary.
You can also solder directly to the contacts. The wiring is fairly
simple as shown in the illustration below.

To add color,
refer to last month’s article for a complete description of using gel
(color media, Lee, Rosco, GAM etc.) to enhance the effect.

Next
month I will be on vacation, but in August’s column we will take a look
at the centuries old but still effective, “Silk Streamer Fire Effect".
Hope you enjoy the articles, have a nice summer.